In a small bowl, whisk together flour, baking powder, and baking soda. Set aside.
Combine the butter and sugar in the bowl of a stand mixer fitted with the paddle attachment. Mix to combine, increase speed to medium, and beat until fluffy, scraping down the sides of the bowl as needed, about 3 minutes.
Add egg and beat in completely.
Add the flour mixture in three additions, alternating with two additions of the buttermilk, mixing just long enough to combine between additions.